Remove workaround for strangely-sized component.

When adding the new app info header, I had to manually specify its
height to avoid it taking up the whole screen.  That bug has been
fixed, so I can remove my workaround.

I'm also making its margins more consistent with other uses of this
header.

Test: Visually inspect header and see it similar to existing ones.
Change-Id: I623b68a2d32593c8e31e359717272dfa6cc0baea